Mucus secretion is a normal function of respiratory mucous membranes. Models for measurement of mucus production by cultured human bronchial and nasal mucosae have been developed in order to examine the controls of mucus secretion. In addition to neurohormones and mediators of allergy, airways react to a product generated by pulmonary macrophages with increased mucus release. Macrophages produce a low molecular weight substance (known as MMS or macrophage-derived mucus secretagogue) after phagocytosis which is a potent secretagogue. MMS is newly synthesized by an oligomycin-sensitive pathway, filters with an apparent molecular weight of 2000 daltons, is not an arachidonic acid derivative, and has a pI of 5.15. MMS release is stimulated by activated zymosan but not by non-activated zymosan, protein A-containing staph but not by non-protein A staph, and concanavalin A, but not by latex. MMS may play a role in mucorrhea associated with macrophage activation. Nasal turbinates secrete a family of acidic glycoproteins which range in size from 0.2-20 million daltons. These glycoproteins are homogeneous in charge and isoelectric focusing (pI-2.6) and consist of 80% carbohydrate and 20% protein. Cholinergic, alpha adrenergic and immunologic stimulation increase nasal turbinate mucous glycoprotein release.